LORATADINE REDIDOSE
Clinical safety rating: safe
No significant drug interactions at recommended doses Rarely may cause headache or somnolence.
Selective peripheral H1 receptor antagonist; inhibits histamine release from mast cells.
| Metabolism | Hepatic via CYP3A4 and CYP2D6; active metabolite desloratadine. |
| Excretion | Renal (approximately 40% as metabolites), biliary/fecal (approximately 60% as metabolites). Less than 1% excreted unchanged in urine. |
| Half-life | Terminal elimination half-life is 8–14 hours (mean ~12 hours) for desloratadine (active metabolite); parent loratadine half-life ~3–20 hours (mean ~8 hours). Clinically, once-daily dosing maintains steady state in 5–7 days. |
| Protein binding | Loratadine: ~97% bound to plasma proteins (albumin and alpha-1-acid glycoprotein). Desloratadine: ~82–87% bound. |
| Volume of Distribution | Loratadine: Vd ~119 L (approximately 1.7 L/kg for a 70 kg adult). Desloratadine: Vd ~338 L (approximately 4.8 L/kg). Indicates extensive tissue distribution. |
| Bioavailability | Oral bioavailability is not well-defined due to extensive first-pass metabolism; absolute bioavailability is approximately 45–60% for loratadine. Desloratadine has high oral bioavailability (>80%). |
| Onset of Action | Oral: Onset of antihistaminic effect occurs within 1–3 hours, with maximal effect at 4–6 hours. |
| Duration of Action | Duration of action is approximately 24 hours, allowing once-daily dosing. Clinical effect persists beyond 24 hours in some patients. |
10 mg orally once daily
| Dosage form | TABLET, ORALLY DISINTEGRATING |
| Renal impairment | No adjustment required for GFR ≥10 mL/min. For GFR <10 mL/min, use every other day dosing (10 mg every 48 hours). |
| Liver impairment | Child-Pugh Class A: 10 mg orally once daily. Child-Pugh Class B or C: 10 mg orally every other day. |
| Pediatric use | Children 2–5 years: 5 mg orally once daily. Children ≥6 years: 10 mg orally once daily. |
| Geriatric use | No specific adjustment required; use with caution due to potential for increased anticholinergic effects and renal impairment. Start at 10 mg orally once daily. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions at recommended doses Rarely may cause headache or somnolence.
| FDA category | Animal |
| Breastfeeding | Loratadine is excreted into breast milk in small amounts; the M/P ratio is approximately 0.5. Peak milk concentration occurs about 2-3 hours after dosing. The estimated dose to the infant is about 1-2% of the maternal weight-adjusted dose. Generally considered compatible with breastfeeding, but monitor infant for sedation or irritability. |
| Teratogenic Risk |
■ FDA Black Box Warning
None.
| Common Effects | urticaria |
| Serious Effects |
Hypersensitivity to loratadine or any component of the formulation; severe hepatic impairment (Child-Pugh class C).
| Precautions | Use with caution in patients with hepatic or renal impairment; avoid in acute asthma attacks; potential for somnolence (rare at recommended doses). |
Loading safety data…
| Loratadine is categorized as FDA Pregnancy Category B. No teratogenic effects have been observed in animal studies, and no well-controlled studies in pregnant women. There is no evidence of increased risk of major birth defects in first trimester exposure based on human data. |
| Fetal Monitoring | No specific monitoring required beyond routine prenatal care. Monitor pregnant women with severe hepatic impairment (Child-Pugh class C) as clearance may be reduced. |
| Fertility Effects | No known adverse effects on human fertility. Loratadine did not impair fertility in animal studies at doses up to 20 times the human dose. |